Clean extinguishing media (gases) include halons, halon alternatives, and inert gases, and these gases are used in complete immersion fire extinguishing systems for sealed areas to avoid exposing the occupants of these areas to severe health damage that may lead to death, provided that the design rules and the optimal installation of such systems are followed. The main between carbon dioxide and clean media (gases) is the toxicity limit for those gases in sealed areas, where extinguishing concentrations of carbon dioxide exceed the toxicity limit, and in contrast, the extinguishing concentrations of the clean media (gases) do not exceed the toxic limits of those media, Halons have been included among the substances that cause damage to the stratospheric ozone layer, and with the application of the Montreal Protocol to substances that cause damage to the ozone layer, halon production was stopped in developed countries by the year 1994 AD, and it is currently being phased out in the last developing countries that produce halons. Several halon fire extinguishing systems that were installed prior to the entry into force of that protocol are currently in use around the world Recycled halons serve in systems that provide protection for mobile military equipment, aviation systems, and explosion prevention systems, and the transition to the use of alternative media to halons is progressing smoothly, and the American Fire Protection Foundation has issued specification No. (NFPA 12A), and specification No. (NFPA 2001) to regulate the use of halons, halon alternatives, and inert gases in fixed extinguishing systems applications, and clean extinguishing media (gases) are defined as those rapidly evaporating media that leave no residue, and halon alternatives are divided into two categories:
1- compounds (halocarbons)
2- Inert gases and mixture of inert gases (example: nitrogen, argon, and their mixtures)
Clean halocarbon media (s) have several common characteristics as follows:
1- All are not electrically conductive
2- All of them evaporate quickly and leave no residue
3- All are liquefied gases or have a similar behavior
4- All of them can be stored or emptied by equivalent halon 1301 gas systems
5- All of them use high pressure nitrogen gas in most applications as a vacuum catalyst
6- All of them are suitable for use in total immersion applications
7- All of them are less efficient than halon 1301, in terms of the weight and volume of the gas required, all of them require a larger storage capacity
8- All of them have more decomposition products than halon 1301, taking into account the same type of fire, its size, and the same discharge time
As for the inert gases, they are stored as compressed gases, and therefore they require a larger storage volume of halocarbons, and they are also not conductive of electricity, and they form a stable mixture in the air and leave no residue.
Clean media (gases) work to extinguish fires through a set of mechanisms of a chemical and physical nature depending on the type of medium used, as halons chemically extinguish fires by inhibiting the chemical reaction of combustion, while other halocarbons extinguish fires primarily by absorbing heat From the flames during chemical decomposition, which reduces its temperature to a lower degree than that required for the continuation of the combustion reaction, through a combination of heat evaporation processes, heat absorption according to heat capacity, and decomposition by absorbing heat, while inert gases quench the flame by reducing Concentration of oxygen in the environment surrounding the flame, raising the heat capacity of that environment, which helps to cool down and reduce the temperature to below the ignition temperature and then inhibit combustion reactions, and the minimum extinguishing concentrations are determined in total immersion systems for Class (A) fires through An approval process includes several tests conducted by a neutral party. As for class (B) fires, extinguishing concentrations are determined by the vessel method. Cup burner, and total immersion systems are also used in protection systems against explosions by converting the protected area to a chemically inert environment, and the required gas concentration is defined as the concentration required to prevent an increase in pressure beyond acceptable limits in a mixture of air, fuel, and extinguishing medium. When exposing that mixture to the source of ignition, and these systems are designed according to each application due to the absence of general requirements or design standards available, and their design depends on emptying the extinguishing medium very quickly after early detection of the occurrence of ignition, and the limits of gas toxicity is one of the main factors that must be taken into consideration A consideration when it comes to the use of clean media (gases) in fire protection, and toxicity tests are performed on the following grounds:

1- Duration of exposure to gas, and frequency of exposure to gas
2- Determine the biological effects of exposure to gas
From the results of these tests, the value of the (NOAEL) and (LOAEL) concentration is obtained for each extinguishing medium, and the (NOAEL) concentration is defined as the highest concentration. Upon reaching it, no harmful effect on people exposed to the gas is noticed, while the (LOAEL) concentration is known as At the lowest concentration, the harmful effect on people exposed to the gas is observed. Extinguishing systems are designed using halocarbons at concentrations lower than the concentration of (NOAEL). In contrast, the inert gases do not expose the user to any physiological damage, and the main physiological harm to their use is low The oxygen concentration resulting from the high gas concentrations used in the design, where inert gases with extinguishing concentrations of up to 43% (equivalent to 12% oxygen remaining for breathing) can be used in areas where occupants are located, and there are two main types of environmental impacts that must be considered when The use of halocarbons are:
1- The ozone layer is damaged
2- Global warming
The ozone layer destructive power factor (ODP) is used to determine the effect of halocarbons on the ozone layer, and it is a measure of the relative amounts of ozone depleted compared to a standard chosen, and the life span of gas in the atmosphere is also used to determine the environmental impact of this gas being emitted into the atmosphere , Where the emission of gases with a long life span into the atmosphere is restricted not because they are harmful, but because of the uncertainty of the extent of their harm or benefit, and the global warming power factor (GWP) is used to study the global warming resulting from the use of those gases, and the power factor is defined. On global warming (GWP) as a relative measure of the heat produced by greenhouse gases in the atmosphere, where the amount of latent heat in a specific mass of a particular gas is compared with the latent heat with the same mass of carbon dioxide, provided that this is calculated over a specific period of time. Phase-out of all chemicals that have an ozone-destroying factor (ODP) of more than zero according to the Montreal Protocol. HFCs and Perfluorocarbons are part of the group of industrial gases included in the Kyoto Protocol, which are subject to emission controls in the signatory countries to this protocol, yet they represent less than 1% of greenhouse gas emissions used in extinguishing systems on a carbon equivalent basis, a percentage whose effect is neglected when studying Greenhouse gases, and the media (gases) are used in fixed extinguishing systems in one of the following two ways:
1- Total immersion systems
These systems provide protection from fire risks in closed or partially closed areas at the very least, and they are either engineering systems that are designed or pre-engineered systems, and engineering systems are specially designed for each risk using pre-approved system components that have a wide range of characteristics. Performance, and these components provide an unlimited number of system shapes that are commensurate with these risks, and on the other hand, pre-engineered systems have a number of system components and predefined shapes, and those components are included in the system approval list, and total immersion systems are classified into two types Two foundations are the modular systems and the central systems, and the modular systems consist of groups consisting of one or several individual cylinders connected to the system’s sprinklers, and these systems are lower in the initial cost while the cost of maintenance increases, and for the central systems, all gas cylinders are installed in them in one place Central, piping networks are used to distribute and discharge gas from sprinklers at various locations.
Advantages of total flood extinguishing systems:
1- The ability to extinguish fires, to which direct access is blocked by any obstacles, in areas with non-standard engineering designs, as well as three-dimensional fires

2- The ability to put out fires very early before the occurrence of any direct or indirect damage from the impact of fire or smoke, by using the appropriate type of automatic fire alarm systems
3- The ability not to cause any collateral damage as a result of discharging the gas2- Local fire extinguishing systems
These systems empty the extinguishing medium in the vicinity of the burning material, so that this environment contains a high concentration of this medium, which leads to extinguishing the fire.

Clean extinguishing media (gases) include halons, halon alternatives, and inert gases, and these gases are used in complete immersion fire extinguishing systems for sealed areas to avoid exposing the occupants of these areas to severe health damage that may lead to death, provided that the design rules and the optimal installation of such systems are followed. The main between carbon dioxide and clean media (gases) is the toxicity limit for those gases in sealed areas, where extinguishing concentrations of carbon dioxide exceed the toxicity limit, and in contrast, the extinguishing concentrations of the clean media (gases) do not exceed the toxic limits of those media, Halons have been included among the substances that cause damage to the stratospheric ozone layer, and with the application of the Montreal Protocol to substances that cause damage to the ozone layer, halon production was stopped in developed countries by the year 1994 AD, and it is currently being phased out in the last developing countries that produce halons. Several halon fire extinguishing systems that were installed prior to the entry into force of that protocol are currently in use around the world Recycled halons serve in systems that provide protection for mobile military equipment, aviation systems, and explosion prevention systems, and the transition to the use of alternative media to halons is progressing smoothly, and the American Fire Protection Foundation has issued specification No. (NFPA 12A), and specification No. (NFPA 2001) to regulate the use of halons, halon alternatives, and inert gases in fixed extinguishing systems applications, and clean extinguishing media (gases) are defined as those rapidly evaporating media that leave no residue, and halon alternatives are divided into two categories:
1- compounds (halocarbons)
2- Inert gases and mixture of inert gases (example: nitrogen, argon, and their mixtures)
Clean halocarbon media (s) have several common characteristics as follows:
1- All are not electrically conductive
2- All of them evaporate quickly and leave no residue
3- All are liquefied gases or have a similar behavior
4- All of them can be stored or emptied by equivalent halon 1301 gas systems
5- All of them use high pressure nitrogen gas in most applications as a vacuum catalyst
6- All of them are suitable for use in total immersion applications
7- All of them are less efficient than halon 1301, in terms of the weight and volume of the gas required, all of them require a larger storage capacity
8- All of them have more decomposition products than halon 1301, taking into account the same type of fire, its size, and the same discharge time
As for the inert gases, they are stored as compressed gases, and therefore they require a larger storage volume of halocarbons, and they are also not conductive of electricity, and they form a stable mixture in the air and leave no residue.
Clean media (gases) work to extinguish fires through a set of mechanisms of a chemical and physical nature depending on the type of medium used, as halons chemically extinguish fires by inhibiting the chemical reaction of combustion, while other halocarbons extinguish fires primarily by absorbing heat From the flames during chemical decomposition, which reduces its temperature to a lower degree than that required for the continuation of the combustion reaction, through a combination of heat evaporation processes, heat absorption according to heat capacity, and decomposition by absorbing heat, while inert gases quench the flame by reducing Concentration of oxygen in the environment surrounding the flame, raising the heat capacity of that environment, which helps to cool down and reduce the temperature to below the ignition temperature and then inhibit combustion reactions, and the minimum extinguishing concentrations are determined in total immersion systems for Class (A) fires through An approval process includes several tests conducted by a neutral party. As for class (B) fires, extinguishing concentrations are determined by the vessel method. Cup burner, and total immersion systems are also used in protection systems against explosions by converting the protected area to a chemically inert environment, and the required gas concentration is defined as the concentration required to prevent an increase in pressure beyond acceptable limits in a mixture of air, fuel, and extinguishing medium. When exposing that mixture to the source of ignition, and these systems are designed according to each application due to the absence of general requirements or design standards available, and their design depends on emptying the extinguishing medium very quickly after early detection of the occurrence of ignition, and the limits of gas toxicity is one of the main factors that must be taken into consideration A consideration when it comes to the use of clean media (gases) in fire protection, and toxicity tests are performed on the following grounds:

1- Duration of exposure to gas, and frequency of exposure to gas
2- Determine the biological effects of exposure to gas
From the results of these tests, the value of the (NOAEL) and (LOAEL) concentration is obtained for each extinguishing medium, and the (NOAEL) concentration is defined as the highest concentration. Upon reaching it, no harmful effect on people exposed to the gas is noticed, while the (LOAEL) concentration is known as At the lowest concentration, the harmful effect on people exposed to the gas is observed. Extinguishing systems are designed using halocarbons at concentrations lower than the concentration of (NOAEL). In contrast, the inert gases do not expose the user to any physiological damage, and the main physiological harm to their use is low The oxygen concentration resulting from the high gas concentrations used in the design, where inert gases with extinguishing concentrations of up to 43% (equivalent to 12% oxygen remaining for breathing) can be used in areas where occupants are located, and there are two main types of environmental impacts that must be considered when The use of halocarbons are:
1- The ozone layer is damaged
2- Global warming
The ozone layer destructive power factor (ODP) is used to determine the effect of halocarbons on the ozone layer, and it is a measure of the relative amounts of ozone depleted compared to a standard chosen, and the life span of gas in the atmosphere is also used to determine the environmental impact of this gas being emitted into the atmosphere , Where the emission of gases with a long life span into the atmosphere is restricted not because they are harmful, but because of the uncertainty of the extent of their harm or benefit, and the global warming power factor (GWP) is used to study the global warming resulting from the use of those gases, and the power factor is defined. On global warming (GWP) as a relative measure of the heat produced by greenhouse gases in the atmosphere, where the amount of latent heat in a specific mass of a particular gas is compared with the latent heat with the same mass of carbon dioxide, provided that this is calculated over a specific period of time. Phase-out of all chemicals that have an ozone-destroying factor (ODP) of more than zero according to the Montreal Protocol. HFCs and Perfluorocarbons are part of the group of industrial gases included in the Kyoto Protocol, which are subject to emission controls in the signatory countries to this protocol, yet they represent less than 1% of greenhouse gas emissions used in extinguishing systems on a carbon equivalent basis, a percentage whose effect is neglected when studying Greenhouse gases, and the media (gases) are used in fixed extinguishing systems in one of the following two ways:
1- Total immersion systems
These systems provide protection from fire risks in closed or partially closed areas at the very least, and they are either engineering systems that are designed or pre-engineered systems, and engineering systems are specially designed for each risk using pre-approved system components that have a wide range of characteristics. Performance, and these components provide an unlimited number of system shapes that are commensurate with these risks, and on the other hand, pre-engineered systems have a number of system components and predefined shapes, and those components are included in the system approval list, and total immersion systems are classified into two types Two foundations are the modular systems and the central systems, and the modular systems consist of groups consisting of one or several individual cylinders connected to the system’s sprinklers, and these systems are lower in the initial cost while the cost of maintenance increases, and for the central systems, all gas cylinders are installed in them in one place Central, piping networks are used to distribute and discharge gas from sprinklers at various locations.
Advantages of total flood extinguishing systems:
1- The ability to extinguish fires, to which direct access is blocked by any obstacles, in areas with non-standard engineering designs, as well as three-dimensional fires

2- The ability to put out fires very early before the occurrence of any direct or indirect damage from the impact of fire or smoke, by using the appropriate type of automatic fire alarm systems
3- The ability not to cause any collateral damage as a result of discharging the gas2- Local fire extinguishing systems
These systems empty the extinguishing medium in the vicinity of the burning material, so that this environment contains a high concentration of this medium, which leads to extinguishing the fire.